First thought that pops in your head when you hear "The Trilogy"?

Star Wars. Though LOTR is a strong contender.  
 
EDIT: Changed my mind. It's Sex, Drugs and Rock & Roll. 

Star Wars.

I think this is going to be unanimously Star Wars.

That scene in Clerks 2 where they argue this.
 
 

Indiana Jones! No I'm just kidding, Star Wars.

Tea, toast and telly.
 
EDIT: 
 
Just noticed this is my 333rd post. 
 
Mind blown.
 
EDIT 2:
 
Editing your posts counts as a post.
 
What is real anymore? Fuck.

" Tea, toast and telly. "

Star Wars for me too.

Depends. 
Sometimes I think of Star Wars, sometimes Back to the Future

Star Trek II, III, and IV.

Matrix, then Star Wars.

Yeah, Star Wars. As far as I'm concerned, they invented the word.

Star Wars Episodes IV, V, and VI...obviously.

Lord of the Rings i guess, at least in this moment. i'm going to try it again tomorrow maybe my answer change

Maybe some of you aren't aware of the official policy of permabanning anyone who blasphemes the original Star Wars trilogy...it's in the Terms & Conditions you know.

" That scene in Clerks 2 where they argue this. "

Star Wars, LOTR.
 
Mass Effect aswell in a few years =P

LOTR

Yeah, I'd have to go with Star Wars

" Mortal Kombat Trilogy. "

I think of something made of three parts.
 
Deep, huh?
 
Runner up: Star Wars/Dune

Star Wars.  The original trilogy.

Lord of the Rings.
I read the books when I was younger, but wasn't really into Star Wars until after KotOR.

I don't associate the words "The Trilogy" with the Star Wars' original trilogy for some reason, even though that's the one I would say I probably was affected by the most. The Lord of the Rings trilogy seemed to be sold as "The Trilogy" from the outset. The books were "The Trilogy" and the movies were "The Trilogy" whereas Star Wars was like "Hey three movies in chronological order"
When you ask me what do I think when you say "episode", I immediately think Star Wars. When you say "Return of the..." I immediately think "Jedi"
But for some reason, "The Trilogy" sounds like Lord of the Rings to me.

A real dirty three-way...  Like, three huge gay truckers...  That's hot!

LOTR.

" Mortal Kombat Trilogy. "

Has to be star wars.

"That scene in Clerks 2 where they argue this."

For me...
 
Ass
Tits
Legs
 
There is no other answer.

Star Wars...the originals....not the new super shitty ones. 

" Star Wars. Though LOTR is a strong contender.   EDIT: Changed my mind. It's Sex, Drugs and Rock & Roll.  "

Star Wars

yep star wars

Star Wars

Spider-Man

star wars of course

Star Wars for sure.

Matrix and LOTR.
I didn't think of starwars because i think of the movies as a whole 6 and not really like 2 trilogies.

LOTR for me.

Star Wars

Easily Star Wars, but that's because I am a huge Star Wars nerd.

LOTR

The Evil Dead trilogy or The Vengeance trilogy

Matrix

Alien(s). Always has.